Recently, display technologies have been developed rapidly. For example, Thin film transistor (simply referred as TFT) technologies have been developed from amorphous silicon thin-film transistors in the past to low temperature Poly-Si thin film transistors, metal oxide semiconductor thin film transistors and so on currently. Phosphor technologies have been developed from liquid crystal display (simply referred as LCD) technologies in the past to organic light emitting diode (simply referred as OLED) technologies currently.
Oxide semiconductors are highly regarded. Large-sized oxide panels are currently in a phase of mass production and backplane performance promotion. Mass produced oxide backplanes are substantially etch-stopper layer (simply referred as ESL) structures. Because a display screen is required to have a high definition all the time, it requires a pixel area to be reduced continuously and Pixels Per Inch (simply referred as PPI) to be increased. However, the pixel area being reduced continuously would lead to a problem of process complexity and reliability, and storage capacitance being continuously decreased.